Structural, optical, electrical properties, and relative humidity sensor application of PVA/Dextrin polymeric blend loaded with silicon dioxide nanoparticles

In the current study, polymer composite films (PCFs) of polyvinyl alcohol (PVA) and Dextrin (60/40) wt% without and with 0.03 and 0.06 wt% silicon dioxide nanoparticles (SiO 2 NPs) were synthesized via casting way. The structural properties of the matrix polymer blend (MPB) were investigated using X-ray diffraction and revealed an amorphous structure. However, some kind of crystallinity has appeared after embedding the SiO 2 NPs. The chemical functional groups were analyzed via FTIR spectra. The surface morphology characteristics were performed utilizing an optical microscope (OPM), and the images showed that SiO 2 NPs were well diffused in MPB without any agglomerations. The optical properties were studied in the wavelength range between 190 and 1100 nm. Up to 97% of UV rays were blocked by PCFs at λ = 270 nm and the absorption edges decreased from 4.05 to 3.80 eV. The values of the allowed and forbidden energy gap ( E g ) decreased from 4.18 to 3.75 eV and from 3.98 to 3.73 eV, respectively, with the existence of the NPs. In addition, the electrical conductivity ( σ ac ) values were increased with the increase in frequency f and NPs content. The use of SiO2NPs has shown highly improved dielectric and energy dissipation characteristics and has a high sensitivity to relative humidity in various NPs ratios, temperatures, time and RH ranges.